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<h1>libdill: Structured Concurrency for C</h1>

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<h1 id="name">NAME</h1>
<p>term_attach - creates TERM protocol on top of underlying socket</p>
<h1 id="synopsis">SYNOPSIS</h1>
<div class="sourceCode"><pre class="sourceCode c"><code class="sourceCode c"><span class="pp">#include </span><span class="im">&lt;libdill.h&gt;</span>

<span class="dt">int</span> term_attach(
    <span class="dt">int</span> s,
    <span class="dt">const</span> <span class="dt">void</span>* buf,
    <span class="dt">size_t</span> len,
    <span class="dt">int64_t</span> deadline);</code></pre></div>
<h1 id="description">DESCRIPTION</h1>
<p>TERM is a protocol that implements clean terminal handshake between peers. When creating the protocol instance user specifies the terminal message to use. When closing the protocol, terminal messages are exchanged between peers in both directions. After the protocol shuts down the peers agree on their position in the message stream.</p>
<p>This function instantiates TERM protocol on top of the underlying protocol.</p>
<p><strong>s</strong>: Handle of the underlying socket. It must be a message protocol.</p>
<p><strong>buf</strong>: The terminal message.</p>
<p><strong>len</strong>: Size of the terminal message, in bytes.</p>
<p><strong>deadline</strong>: A point in time when the operation should time out, in milliseconds. Use the <strong>now</strong> function to get your current point in time. 0 means immediate timeout, i.e., perform the operation if possible or return without blocking if not. -1 means no deadline, i.e., the call will block forever if the operation cannot be performed.</p>
<p>The socket can be cleanly shut down using <strong>term_detach</strong> function.</p>
<p>This function is not available if libdill is compiled with <strong>--disable-sockets</strong> option.</p>
<h1 id="return-value">RETURN VALUE</h1>
<p>In case of success the function returns newly created socket handle. In case of error it returns -1 and sets <strong>errno</strong> to one of the values below.</p>
<h1 id="errors">ERRORS</h1>
<ul>
<li><strong>EBADF</strong>: Invalid handle.</li>
<li><strong>ECANCELED</strong>: Current coroutine was canceled.</li>
<li><strong>EMFILE</strong>: The maximum number of file descriptors in the process are already open.</li>
<li><strong>ENFILE</strong>: The maximum number of file descriptors in the system are already open.</li>
<li><strong>ENOMEM</strong>: Not enough memory.</li>
<li><strong>ENOTSUP</strong>: The handle does not support this operation.</li>
<li><strong>EPROTO</strong>: Underlying socket is not a message socket.</li>
<li><strong>ETIMEDOUT</strong>: Deadline was reached.</li>
</ul>
<h1 id="example">EXAMPLE</h1>
<div class="sourceCode"><pre class="sourceCode c"><code class="sourceCode c">s = term_attach(s, <span class="st">&quot;STOP&quot;</span>, <span class="dv">4</span>);
...
<span class="co">/* Send terminal message to the peer. */</span>
term_done(s, <span class="dv">-1</span>);
<span class="co">/* Process remaining inbound messages. */</span>
<span class="cf">while</span>(<span class="dv">1</span>) {
    <span class="dt">char</span> buf[<span class="dv">256</span>];
    <span class="dt">ssize_t</span> sz = mrecv(s, buf, <span class="kw">sizeof</span>(buf), <span class="dv">-1</span>);
    <span class="co">/* Check whether terminal message was received from the peer. */</span>
    <span class="cf">if</span>(sz &lt; <span class="dv">0</span> &amp;&amp; errno == EPIPE) <span class="cf">break</span>;
    frobnicate(buff, sz);
}
s = term_detach(s);</code></pre></div>
<h1 id="see-also">SEE ALSO</h1>
<p><strong>hclose</strong>(3) <strong>mrecv</strong>(3) <strong>mrecvl</strong>(3) <strong>msend</strong>(3) <strong>msendl</strong>(3) <strong>now</strong>(3) <strong>term_attach_mem</strong>(3) <strong>term_detach</strong>(3) <strong>term_done</strong>(3)</p>
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